Activity of azacitidine in chronic myelomonocytic leukemia

Hypomethylating drugs are useful in the management of myelodysplastic syndrome (MDS). Two of these drugs, azacitidine and decitabine, have received FDA approval for the treatment of MDS and chronic myelomonocytic leukemia (CMML). However, phase 2 and 3 studies that assessed these agents in MDS included only a small number of patients with CMML. The objective of this study was to evaluate the efficacy and safety of azacitidine in the treatment of CMML.

The records of thirty-eight patients diagnosed with CMML and treated with azacitidine at our institution were reviewed. Azacitidine was administered at 75 mg/m(2) /day for 7 days or 100 mg/m(2) /day for 5 days every 4 weeks. Patients who received at least 1 cycle of the drug were considered evaluable for response.

Response was assessed by the modified International Working Group (IWG) criteria. The overall response rate was 39% (14 of 36); complete response (CR) rate was 11% (4 of 36); partial response (PR) rate was 3% (1 of 36); hematologic improvement (HI) was 25% (9 of 36). The median overall survival was 12 months. There was a statistically significant overall survival advantage in responders compared with nonresponders: 15.5 months versus 9 months, respectively (P = .04). Treatment was generally well tolerated. One of 2 patients had complete resolution of a skin rash that was due to monocytic infiltration.

Azacitidine is active in the treatment of CMML. The therapy-associated toxicity is acceptable. Our results support further investigation of azacitidine in CMML, particularly in combination with other agents.